Hot-water heating system



April 15, 1952 FRENGER 2,592,887

HOT-WATER HEATING SYSTEM Filed Feb. 7, 1947 Patented Apr. 15, 195:2

Application February 7, 1947, Serial No. 727,004 In Norway October 20,1939 Section 1, Public Law 690, August 8, 1946 Patent expires October20, 1959 Claims.

The present invention relates to hot water boilers, and especially hotwater boilers of the type having a water jacket (that is a hollow wallfilled with water and surrounding the furnace proper) and an economiserportion (that is a heating surface located outside of the furnace properand subjected to the action of the combustion gases), preferably forstoker or wood firing.

Boilers of said type are extensively used, especially in connection withstoker furnaces, due to the material advantages derived from the use ofsuch boilers. However, corrosion of the heating surfaces of such boilersis frequently observed in hot water boilers of this type. This is due tothe fact, that in operation of hot water boiler systems it is necessaryto use such low temperatures, that the water vapours contained in thecombustion gases are condensed upon the water cooled heating surfaces ofthe boiler. For obviating this drawback it has been suggested that suchheating systems being provided with a so-called shunt couplingarrangement enabling the boiler to be operated at a high watertemperature of say 80-90 C. This arrangement, however, does not removethe objectionable corrosion feature because of the fact that the waterreturning from the heating system or radiators is returned into theboiler at so low a temperature, especially in the period of transition,that parts of the boiler surfaces attain a temperature lower than thecondensation temperature of water vapour at the partial pressure inquestion, as a rule about 40 C. This will cause corrosion of the boilersurfaces, the sulphur of the fuel, now contained in the combustiongases, forming sulphuric acid and sulphurous acid, which in short timemay fret through the boiler surfaces. The parts most vu1- nerable inthis respect are those parts of the boiler surfaces which are locatedoutside of the furnace and which consequently are not directly touchedor irradiated by the flames. Thus the economiser portion of the boiler,which is per sev the least accessible part, is corroded to a substantialdegree.

The present invention aims at obviating the drawbacks mentioned above,and comprises to that end several features and arrangements in hot waterboilers of the type in question, which features and arrangements will beexplained below.

The annexed drawing illustrates by way of example embodiments of a hotWater boiler according to the invention.

Fig. 1 shows a vertical section thereof on the line A-A in Fig. 2.

Fig. 2 is a horizontal projection, the top half of which shows a sectionon the line 11-15 in Fig. l, and the lower half of which shows a sectionon the line E-E in Fig. 1. v

Fig. 3 shows a section on the line B'-'B in Fig. 1.

Fig. 4 illustrates on a larger scale a section through the upper wall ofthe header.

Figs. 5 and 6 show, in perspective view and in vertical sectionrespectively, a modification ac cording to the invention.

Figures 1-3 show a stoker boiler, which I is the furnace space, which issurrounded by a jacket.

The combustion gases flow from the furnace l throrgh the gas flue 3 ofthe boiler into the exit flue The interior path of the circulationsystem of the boiler may be traced as follows: starting at 5, thecirculation moves downwards in the front jacket 2, through the openings6 at the bottom of the bciler into the lateral side jacket 1. Here aportion of the boiler water rises into the box [8, whereas anotherportion proceeds through openings 9 and is distributed into a set oftubes ID, from where it passes through collecting headers I l into saidmixing box [8.

In order to assist this interior path of circulation, transversepartitions such as at 2 I, may be arranged in the top portion of theboiler as shown,

which partitions divide the water jacket area into two parts or zones,in such a manner that the water will flow downwards in one of the Zonesat 5 in jacket 2 (at the left in Fig. 1) and upwards in the other zoneconsisting of the side jackets l and the back jacket (at the right inFig. 1).

In the boiler the highest temperature will be attained. at 8, and thelowest temperature at 5. The outer circulatory path extends fromtubulation [2 into the collecting chamber l3 and through holes M in thebottom of the mixing" box l8 into said mixing box to the area [5 and outthrough the tubulation l6, so that the colder return water is introducedat l2, the warm water leaving at l6. Through the holes I4, which arepreferably inclined in forward direction towards the front side of themixing box, the cold return water is intimately mixed in the mixing boxl8 'above the holes M with the hottest Water coming 3 from 8, wherebythe temperature of the water leaving the boiler at IE will besubstantially equal to the temperature of the water re-entering theinterior path of the circulation system of the boiler at 5.

The result of the present invention is that no surface of the boiler,normally susceptible to corrosion has a temperature lower than thetemperature of the Water passing to the outer circulation system, and ifthe temperature of the outgoing water is at all times kept above thetemperature critical to corrosion, which as a rule is about 40-45 C., nodeposit of tars or similar materials will occur in the boiler, andcorrosion due to too low water temperature will be eliminated.

It is not always practical to let the return water conduit or conduitsopen directly into the space for transient flow, and in such cases thereturn water pipe from which the return water passes into the space fortransient flow may, according to the invention; enter into a separatecollecting chamber, below the mixing chamber which collecting chamber isthus situated in a part of the furnace less subjected to corrosion andthe like, so that the cold return water will first flow along a heatingsurface, on which a low water temperature is substantially harmless.

As will be seen a very thorough mixing of boiler water and return wateris obtained, and the inclined outlet openings l4 (see Fig. 4) areeffective to increase the circulation in the boiler.

Moreover the said circulations will take place, as shown, in a naturalway due to the temperature differences, and due to the relativearrangement of the return water inlet.

In hot water boilers of this general design it has been suggested toprovide a wall, as indicated at 2B in Fig. 1, extending from the bottomof the water jacket I, so that the heater water contained within thefurnace walls is provided with added heating surface prior to theintroduction of said water into the tube set. While such an arrangementis not necessary in this connection, it may be used, if desired.

In the embodiment shown in Figs. 1 to 3 inclusive, the openings M forinlet of return water are situated between that opening through whichthe hot water flows into the space for transitory flow, and the openingfor downward flow.

The invention is, however, not restricted to the embodiment of Figs. 1,2 and 3. Thus the inlet of return water may take place topmost, at anyone of the boiler sides, and the like. Thus Fig. 5 is a perspectiveview, and Fig. 6 a vertical section of an embodiment, showing how thedevice in question may be arranged within the water jacket of a boiler.

If it is desired that the water issuing into the outer circulationcircuit shall have a lower temperature than the water entering from l5,a by-pass conduit may be arranged from the chamber 43 through a valve40, so that a portion of the return water is returned to the outercircuit.

This is diagrammatically indicated by dashdotted lines at the upper leftof Fig. l.

The invention is also of great value for heaters fired with wood orpeat, in order that pitch or tar deposits on the heating surfaces shallbe avoided.

I claim:

1. A hot water boiler having a water jacket and an economizer portionprovided with heating surfaces, said economizer portion connected to 4said water jacket in water circulating relation, means providing a spacefor transitory flow and admixing of water of varied temperatures locatedsubstantially at the high point of said jacket, and having inlet meansfor heated water from said jacket, inlet means for heated water fromsaid economizer portion, inlet means for return water, and outlet meansfor heated admixed water, said inlet means and outlet means beingarranged for flow of water therebetween and within said transitory flowspace means in such spaced relation that said return water, the hottestboiler water, and the heated water from said economizer portion areintimately admixed prior to flowing into said outlet.

2. A hot water boiler having a water jacket provided with heatingsurfaces and an economizer portion provided with heating surfaces, saideconomizer portion connected to said water jacket in Water circulatingrelation, means providing a space for transitory flow and admixing ofwater of varied temperatures located at the top of said jacket, andhaving inlet means for heated water from said jacket, inlet means forheated water from said economizer portion, re-

turn water inlet means adjacent the heating surface provided for the topof said jacket, and outlet means for heated admixed water, said inletmeans and outlet means being arranged for flow of water therebetween andwithin said transitory flow space means in such spaced relation thatsaid return water, the hottest boiler water, and the heated water fromsaid economizer portion are intimately admixed prior to flowing intosaid outlet.

3. In a hot water heating system of the type having radiators, a boiler,said boiler including a furnace box, a water jacket surrounding saidfurnace box and an economizer portion connected to said water jacket forcirculation of water from said water jacket through said economizerportion in heat exchange relation and back into said water jacket,outlet pipes connected to the upper area of said water jacket for flowof heated water to said radiators, intake pipes connected to the upperarea of said water jacket for flow of return water from said watercirculating elements, said intake pipes and said outlet pipes being insuch spaced relation that the water flowing into said outlet pipes is anadmixture of said return water and the hottest water contained in saidboiler.

4. In a hot water heating system of the type having separate radiatorsfor heat exchange, a boiler comprising a furnace box, a water jacketsurrounding said furnace box and an economizer portion connected to saidwater jacket and consisting of water conduits heated by the hot fluegases escaping from said furnace box into said economizer portion, saidboiler including inlet means for return water from said radiators to thetop section of said water jacket, inlet means for hot Water from theside and rear sections of said water jacket and from said economizerportion to said top section and outlet means to said radiators from saidtop section, said inlet means and said outlet means being arranged insuch spaced relation that said return water, the hottest boiler waterand the heater water from said economizer portion are intimately mixedprior to flowing into said outlet.

5. In a hot water heating system according to claim 4 wherein the topsection of the water jacket of the boiler is divided into two areas, thelower area comprising a collecting box and the upper area comprising amixing box, said collecting box separated from said mixing box by anapertured platform, said return water inlet means connected to saidcollecting box, said inlet means for hot water from the side and rearsections of said water jacket and from said economizer portion and saidoutlet means connected to said mixing box, whereby said return water isin heat exchange relation with the top heating surface of said furnacebox and flows upwardly through said apertured platform into said mixingbox for admixing.

GUNNAR, FRENGER.

REFERENCE S CITED The following references are of record in the file ofthis patent:

Number Number 15 70,807

UNITED STATES PATENTS Name Date Owen et a1. May 17, 1887 Stettinius July4, 1899 Restner June 25, 1918 Edsen June 29, 1920 Williams June 16, 1925Hulsmeyer June 24, 1930 Ostermann Jan. 7, 1936 Swars Dec. 29, 1936 'KolbJan. 14, 1941 FOREIGN PATENTS Country Date Norway Aug. 5, 1946

